<title>传染病控制</title><link href="http://hzoi.com/tomorrow.css" rel="stylesheet"><div class="ui existing segment"><pre><code><span class="pl-cp">#include</span> <span class="pl-cpf">&lt;bits/stdc++.h&gt;</span><span class="pl-cp"></span>
<span class="pl-k">const</span> <span class="pl-kt">int</span> <span class="pl-n">maxn</span><span class="pl-o">=</span><span class="pl-mi">300</span><span class="pl-o">+</span><span class="pl-mi">5</span><span class="pl-p">,</span><span class="pl-n">Inf</span><span class="pl-o">=</span><span class="pl-mi">2147483647</span><span class="pl-p">;</span>
<span class="pl-kt">int</span> <span class="pl-n">n</span><span class="pl-p">,</span><span class="pl-n">m</span><span class="pl-p">,</span><span class="pl-n">max_dis</span><span class="pl-p">,</span><span class="pl-n">ans</span><span class="pl-o">=</span><span class="pl-mi">2147483647</span><span class="pl-p">;</span>
<span class="pl-kt">int</span> <span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">maxn</span><span class="pl-p">],</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">maxn</span><span class="pl-p">],</span><span class="pl-n">cut</span><span class="pl-p">[</span><span class="pl-n">maxn</span><span class="pl-p">],</span><span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">maxn</span><span class="pl-p">],</span><span class="pl-n">deep</span><span class="pl-p">[</span><span class="pl-n">maxn</span><span class="pl-p">][</span><span class="pl-n">maxn</span><span class="pl-p">],</span><span class="pl-n">cnt</span><span class="pl-p">[</span><span class="pl-n">maxn</span><span class="pl-p">];</span>
<span class="pl-k">struct</span> <span class="pl-n">Edge</span><span class="pl-p">{</span><span class="pl-kt">int</span> <span class="pl-n">next</span><span class="pl-p">,</span><span class="pl-n">to</span><span class="pl-p">;}</span><span class="pl-n">e</span><span class="pl-p">[</span><span class="pl-n">maxn</span><span class="pl-o">&lt;&lt;</span><span class="pl-mi">1</span><span class="pl-p">];</span>
<span class="pl-kt">void</span> <span class="pl-nf">Insert</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">u</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">v</span><span class="pl-p">){</span>
	<span class="pl-n">e</span><span class="pl-p">[</span><span class="pl-o">++</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-mi">0</span><span class="pl-p">]].</span><span class="pl-n">to</span><span class="pl-o">=</span><span class="pl-n">v</span><span class="pl-p">;</span><span class="pl-n">e</span><span class="pl-p">[</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-mi">0</span><span class="pl-p">]].</span><span class="pl-n">next</span><span class="pl-o">=</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">];</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-mi">0</span><span class="pl-p">];</span>
<span class="pl-p">}</span>
<span class="pl-kt">void</span> <span class="pl-nf">dfs</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">now</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">fa</span><span class="pl-p">){</span>
	<span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">now</span><span class="pl-p">];</span><span class="pl-n">i</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-n">e</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">].</span><span class="pl-n">next</span><span class="pl-p">){</span>
		<span class="pl-kt">int</span> <span class="pl-n">v</span><span class="pl-o">=</span><span class="pl-n">e</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-p">;</span>
		<span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">v</span><span class="pl-o">==</span><span class="pl-n">fa</span><span class="pl-p">)</span> <span class="pl-k">continue</span><span class="pl-p">;</span>
		<span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">v</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">now</span><span class="pl-p">]</span><span class="pl-o">+</span><span class="pl-mi">1</span><span class="pl-p">;</span>
		<span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">v</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">now</span><span class="pl-p">;</span>
		<span class="pl-n">max_dis</span><span class="pl-o">=</span><span class="pl-n">std</span><span class="pl-o">::</span><span class="pl-n">max</span><span class="pl-p">(</span><span class="pl-n">max_dis</span><span class="pl-p">,</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">v</span><span class="pl-p">]);</span>
		<span class="pl-n">dfs</span><span class="pl-p">(</span><span class="pl-n">v</span><span class="pl-p">,</span><span class="pl-n">now</span><span class="pl-p">);</span>
	<span class="pl-p">}</span>
<span class="pl-p">}</span>
<span class="pl-kt">void</span> <span class="pl-nf">tag</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">u</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">color</span><span class="pl-p">){</span>
	<span class="pl-n">cut</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">color</span><span class="pl-p">;</span>
	<span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">];</span><span class="pl-n">i</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-n">e</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">].</span><span class="pl-n">next</span><span class="pl-p">){</span>
		<span class="pl-kt">int</span> <span class="pl-n">v</span><span class="pl-o">=</span><span class="pl-n">e</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-p">;</span>
		<span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">v</span><span class="pl-o">==</span><span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">u</span><span class="pl-p">])</span> <span class="pl-k">continue</span><span class="pl-p">;</span>
		<span class="pl-n">cut</span><span class="pl-p">[</span><span class="pl-n">v</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">color</span><span class="pl-p">;</span>
		<span class="pl-n">tag</span><span class="pl-p">(</span><span class="pl-n">v</span><span class="pl-p">,</span><span class="pl-n">color</span><span class="pl-p">);</span>
	<span class="pl-p">}</span>
<span class="pl-p">}</span>
<span class="pl-kt">int</span> <span class="pl-nf">calc</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">dep</span><span class="pl-p">){</span>
	<span class="pl-kt">int</span> <span class="pl-n">sum</span><span class="pl-o">=</span><span class="pl-mi">0</span><span class="pl-p">;</span>
	<span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">cnt</span><span class="pl-p">[</span><span class="pl-n">dep</span><span class="pl-p">];</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">)</span>
		<span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">cut</span><span class="pl-p">[</span><span class="pl-n">deep</span><span class="pl-p">[</span><span class="pl-n">dep</span><span class="pl-p">][</span><span class="pl-n">i</span><span class="pl-p">]]</span><span class="pl-o">==</span><span class="pl-mi">0</span><span class="pl-p">)</span>
			<span class="pl-n">sum</span><span class="pl-o">++</span><span class="pl-p">;</span>
	<span class="pl-k">return</span> <span class="pl-n">sum</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
<span class="pl-kt">void</span> <span class="pl-nf">search</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">dep</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">sum</span><span class="pl-p">){</span>
	<span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">sum</span><span class="pl-o">&gt;=</span><span class="pl-n">ans</span><span class="pl-p">)</span> <span class="pl-k">return</span><span class="pl-p">;</span>
	<span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">dep</span><span class="pl-o">&gt;</span><span class="pl-n">max_dis</span><span class="pl-o">||</span><span class="pl-n">calc</span><span class="pl-p">(</span><span class="pl-n">dep</span><span class="pl-p">)</span><span class="pl-o">==</span><span class="pl-mi">0</span><span class="pl-p">)</span>
		<span class="pl-k">return</span> <span class="pl-n">ans</span><span class="pl-o">=</span><span class="pl-n">std</span><span class="pl-o">::</span><span class="pl-n">min</span><span class="pl-p">(</span><span class="pl-n">ans</span><span class="pl-p">,</span><span class="pl-n">sum</span><span class="pl-p">),</span> <span class="pl-kt">void</span><span class="pl-p">();</span>
	<span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">cnt</span><span class="pl-p">[</span><span class="pl-n">dep</span><span class="pl-p">];</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">){</span>
		<span class="pl-kt">int</span> <span class="pl-n">to</span><span class="pl-o">=</span><span class="pl-n">deep</span><span class="pl-p">[</span><span class="pl-n">dep</span><span class="pl-p">][</span><span class="pl-n">i</span><span class="pl-p">];</span>
		<span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">cut</span><span class="pl-p">[</span><span class="pl-n">to</span><span class="pl-p">]</span><span class="pl-o">==</span><span class="pl-mi">1</span><span class="pl-p">)</span> <span class="pl-k">continue</span><span class="pl-p">;</span>
		<span class="pl-n">tag</span><span class="pl-p">(</span><span class="pl-n">to</span><span class="pl-p">,</span><span class="pl-mi">1</span><span class="pl-p">);</span>
		<span class="pl-n">search</span><span class="pl-p">(</span><span class="pl-n">dep</span><span class="pl-o">+</span><span class="pl-mi">1</span><span class="pl-p">,</span><span class="pl-n">sum</span><span class="pl-o">+</span><span class="pl-n">calc</span><span class="pl-p">(</span><span class="pl-n">dep</span><span class="pl-p">));</span>
		<span class="pl-n">tag</span><span class="pl-p">(</span><span class="pl-n">to</span><span class="pl-p">,</span><span class="pl-mi">0</span><span class="pl-p">);</span>
	<span class="pl-p">}</span>
<span class="pl-p">}</span>
<span class="pl-kt">int</span> <span class="pl-nf">main</span><span class="pl-p">(){</span>
	<span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d%d&quot;</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">n</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">m</span><span class="pl-p">);</span>
	<span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">m</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">){</span>
		<span class="pl-kt">int</span> <span class="pl-n">u</span><span class="pl-p">,</span><span class="pl-n">v</span><span class="pl-p">;</span><span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d%d&quot;</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">u</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">v</span><span class="pl-p">);</span>
		<span class="pl-n">Insert</span><span class="pl-p">(</span><span class="pl-n">u</span><span class="pl-p">,</span><span class="pl-n">v</span><span class="pl-p">);</span><span class="pl-n">Insert</span><span class="pl-p">(</span><span class="pl-n">v</span><span class="pl-p">,</span><span class="pl-n">u</span><span class="pl-p">);</span>
	<span class="pl-p">}</span>
	<span class="pl-n">dfs</span><span class="pl-p">(</span><span class="pl-mi">1</span><span class="pl-p">,</span><span class="pl-mi">0</span><span class="pl-p">);</span>
	<span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">)</span>
		<span class="pl-n">deep</span><span class="pl-p">[</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]][</span><span class="pl-o">++</span><span class="pl-n">cnt</span><span class="pl-p">[</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]]]</span><span class="pl-o">=</span><span class="pl-n">i</span><span class="pl-p">;</span>
	<span class="pl-n">search</span><span class="pl-p">(</span><span class="pl-mi">1</span><span class="pl-p">,</span><span class="pl-mi">1</span><span class="pl-p">);</span>
	<span class="pl-n">printf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d</span><span class="pl-se">\n</span><span class="pl-s">&quot;</span><span class="pl-p">,</span><span class="pl-n">ans</span><span class="pl-p">);</span>
	<span class="pl-k">return</span> <span class="pl-mi">0</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
</cpde></pre></div>